1. Field of Invention
This invention relates to systems and methods for inkjet defect detection.
2. Description of Related Art
There exists printers wherein and inkjet print head moves relative to and ejects marking material toward an intermediate substrate in order to form an image on the intermediate substrate. The inkjet print head includes a number of individual inkjets that each ejects an amount of marking material. Subsequently, the image is transferred from the intermediate substrate onto a sheet of media. The quality of the image formed on the sheet of media is influenced by, among other things, the ability of the individual inkjets to consistently eject ink.
Solid inkjet print heads are prone to develop defects such as clogged inkjets. For example, inkjets within the print head can become clogged such that ink is not consistently ejected. Once an inkjet becomes defective, it will remain defective until the defects are corrected. In other words, the defect that exists in the inkjet is semi-stable because it will not self correct over time. Typically, some maintenance is required in order to correct the inkjet defects. The defect will thus remain with the inkjet until some maintenance is performed. The maintenance may include a purging operation that purges material or air that is clogging the defective inkjet.
Conventionally, in order to determine whether one or more inkjets is defective, an image is printed on a sheet of media utilizing every inkjet of an inkjet print head and the image is visually inspected in order to detect any defects in the inkjets. If the image contains defects, a user can then initiate print head maintenance. However, printing a separate test image and manually initiating maintenance is both system resource (e.g., media, ink, and time that might otherwise be used for productive output) and user resource (e.g., time required to initiate test image, review test image, and initiate maintenance) intensive.
Xerographic devices have addressed the problem of wasted system and user resources by printing test images onto an intermediate substrate within inter-document zones. When images are laid down on the intermediate substrate in xerographic devices, based on the typical system architecture, there is sufficient space between those images on the intermediate substrate to print a test image between the images to be printed. By using an internal image sensor, the xerographic device can evaluate the test image for defects and then perform maintenance on the print head if it is determined to be defective.